Ales Zita Publication Digital Image Forgery Detection Based on Lens and Sensor Aberration Authors Ido Yerushalmy Hagit HelOr Dept of Computer Science University of Haifa Israel ID: 1032021
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1. Digital Image Forgery DetectionAles Zita
2. PublicationDigital Image Forgery Detection Based on Lens and Sensor AberrationAuthors : Ido Yerushalmy , Hagit Hel-Or Dept. of Computer Science, University of Haifa, IsraelPublished in International Journal of Computer Vision DOI 10.1007/s11263-010-0403-1Springer Science + Business Media LLC 2010
3. IntroductionDigital image ageMethods of forgery detectionIntelligent ReasoningAdditional Data EmbeddingStatisticalDetection Without Additional Data
4. Intelligent reasoning
5. MethodsIntelligent reasoningSemantics, geometry, scene lighting, etc..Additional data embeddingWatermarkingStatistics based methodsTraining sets, classification techniques (SVM) Detection Without Additional DataBrute force, JPEG based, CFA based, Chromatic Aberration based
6. Detection w/o additional dataBrute force – detecting duplicates in the feature space (Fridrich at al. 2003)Colour interpolation algorithm scheme discrepancies (Wolfgang and Delp 1996)Repetitive spatial pattern in JPEG compressed images (Wang and Farid 2006)Lens Chromatic Aberration based (Johnson and Farid 2006)
7. Lens Chromatic AberrationsVariety of aberration of optical systemsChromatic Aberration – Snell’s law of refractionSpatial BlurGeometric DistortionLens Chromatic AberrationsAxial Chromatic AberrationLateral Chromatic Aberration (LCA)Achromatic DoubletPurple Fringing Aberration (PFA)
8. Johnson and Farid 2006LCA basedExpansion and contraction of blue & red vs. green channelBrute force algorithm – centre and magnitudeNon overlapping image regions evaluationMark the discrepancies
9. PFABlue-purple halo on the distal and proximal side of bright and dark object edges respectively. Sometimes tiny yellow tint on the opposite side.More acute with high contrast changeStrength increases with is distance from the image centre
10. PFA sourcesCauses:Adjacent photodiode cell electron overflow (Ochi et al. 1997)Sensor infrared filter coating not stopping all the IR (Rudolf 1992)Sensor cell microlenses cause ray refraction to neighboring cells (Daly 2001)
11. PFA Examples
12. AlgorithmIdentify PFA edgesDetermine PFA direction for each eventAssign reliability measure to each eventDetermine the image centerReevaluate directions to detect the inconsistent regions
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17. ReferencesDaly, D. (2001). Microlenses arrays. Boca Raton CRC press.Fridrich, J., Soukal, D., & Lukas, J. (2003). Detection of copy-move forgery in digital images. In Proc. Digital forensic research workshop, Cleveland, OH.Johnson, M. K. & Farid, H. (2006) Exposing digital forgeries through chromatic aberration. On Proc. ACM multimedia and security workshop, Geneva, Switzerland.Ochi, S., Lizuka, T., Sato, Y., Hamasaki, M., Abe, H., Narabu, T., Kato, K., & Kagawa, Y. (1997). Charge-coupled device technology. Boca Raton : CRC press.Rudolf, K. (1992). Optics in photography. Bellingham: SIPE. Yerushalmy&Hel-Or (2010) Digital Image Forgery Detection Based on Lens and Sensor Aberration, International Journal of Computer VisionWang, W., & Farid, H. (2006). Exposing digital forgeries in video by detecting double MPEG compression. In Proc. ACM multimedia and security workshop, Geneva, Switzerland.Wolfgang, R. B., & Delp, E. J., (1996). A watermark for digital images. In Proc. IEEE intl conference on image processing.Wikipedia.org (http://www.wikipedia.org)
18. Thank youQ ?